Fusidic acid derivatives

ABSTRACT

Fusidic acid derivatives which possess anti-bacterial, antimicrobial and pharmacokinetic properties. These derivatives include, for example, 3 alpha ,11 alpha -dihydroxy-16 beta -(2&#39;-methlyphenyl) thiofusida-13(17),24-dien-21-oic acid and pharmaceutically acceptable, non-toxic salts or easily hydrolysable esters thereof.

This is a continuation of application Ser. No. 744,978 filed Nov. 24,1976, now U.S. Pat. No. 4,100,276, the entire specification and claimsof which are hereby incorporated by reference.

The present invention relates to a new series of fusidic acidderivatives, to salts and easily hydrolysable esters thereof, to thepreparation of these compounds and to pharmaceutical compositionscontaining the compounds. The new compounds have the general formula:##STR1## in which Q₁ and Q₂ stand for the group ##STR2## or oxygen, Arepresents oxygen or sulphur, and R₁ stands for a straight or branchedalkyl radical having from 1 to 12 carbon atoms, such as methyl, ethyl,propyl, isopropyl, butyl, isobutyl, tert.butyl, the known isomers ofpentyl, hexyl, heptyl, octyl and dodecyl, such alkyl radicals beingoptionally substituted with halogen atoms or hydroxy, alkyloxy,aralkyloxy, aryloxy, alkanoyloxy, aralkanoyloxy, aroyloxy, sulfhydryl,alkylthio, aralkylthio, arylthio, alkanoylthio, aroylthio, azido, nitro,cyano, thiocyano, hydroxycarbonyl, alkyloxycarbonyl, aryloxycarbonyl,amino, alkylamino, dialkylamino, arylamino, alkanoylamino, andaroylamino groups; R₁ can further be an alkenyl or alkynyl radicalhaving from 3 to 6 carbon atoms, such as allyl, crotyl or propargyl, acycloalkyl radical having from 3 to 7 carbon atoms in the alicyclicring, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl,cycloheptyl, or the mono- or dihalo, lower alkyl, lower alkoxy orhydroxy substituted analogues, an aralkyl or aryl radical, such asbenzyl, phenylethyl, phenyl, furfuryl or naphthyl, optionallysubstituted with halogen, lower alkyl, hydroxy or alkoxy radicals; R₁can also be a heterocyclic radical having 5 to 6 ring atoms andcontaining oxygen, sulphur and/or nitrogen atoms, such as 2- or3-pyrrolyl, 2- or 3-furyl, 2- or 3-thienyl, 2-, 3- or 4-pyridyl, 2-, 4-or 5-pyrimidinyl, 2- or 3-pyrazolyl, imidazolyl e.g.1-methyl-2-imidazolyl, triazolyl, e.g. 5-methyl-1,2,4-triazol-3-yl,tetrazolyl e.g. 1-methyl-1H-tetrazol-5 -yl, thiazolyl, thiadiazolyl e.g.5-methyl-1,3,4-thiadiazol-2-yl.

In formula I the dotted line between C-24 and C-25 indicates that thecarbon atoms in question are connected by either a double bond or asingle bond, and the asterix at C-20 indicates that the compounds existin two diastereomeric forms. The invention comprises the purediastereomers as well as mixtures of these.

Where not otherwise stated the term alkyl in the radicals mentionedabove stands for a C₁ to C₄ alkyl radical.

The compounds of formula I can be used as such or in the form of saltsor easily hydrolysable esters. The salts of the compounds are especiallythe pharmaceutically acceptable, non-toxic salts, such as alkali metalsalts and alkaline earth metal salts, for example sodium, potassium,magnesium or calcium salts, as well as salts with ammonia or suitablenon-toxic amines, e.g. lower alkyl amines for example triethylamine,hydroxy-lower alkylamines, for example 2-hydroxyethylamine,bis-(2-hydroxyethyl)-amine or tri-(2-hydroxyethyl)-amine,cycloalkylamines, for example dicyclohexylamine, or benzylamines, forexample N,N'-dibenzyl-ethylenediamine or dibenzylamine.

For certain purposes also the silver salts of the compounds may be used,especialy for topical treatment.

The easily hydrolysable esters can e.g. be alkanoyloxyalkyl,aralkanoyloxyalkyl, aroyloxyalkyl esters, such as acetoxymethyl,pivaloyloxymethyl, benzoyloxymethyl esters, and the corresponding1'-oxyethyl derivatives, or alkoxycarbonyloxyalkyl esters, such asmethoxycarbonyloxymethyl, ethoxycarbonyloxymethyl and the corresponding1'-oxyethyl derivatives, or lactonyl esters, such as phthalidyl esters,or dialkylaminoalkyl esters, such as diethylaminoethyl esters.

The antibacterial properties of fusidic acid and some newer fusidic acidderivatives against a number of gram-positive bacteria are well known(J. Med. Chem. 9, 15 (1966) and U.S. Pat. application Ser. No. 693,976.

Furthermore another type of fusidic acid derivatives are known toexhibit a more bactericidal effect than these, but against a morelimited number of bacteria (U.S. Pat. No. 3,499,012).

Now, however, it has been found that the compounds of the presentinvention possess antibacterial properties which combine thebactericidal effect of the latter type of derivatives with the broaderantibacterial spectrum of the former type of derivatives, and showfurther interesting antimicrobial and pharmacokinetic properties, bothin vivo and in vitro. Thereby the compounds of the invention can be usedin the treatment of bacterial infections in humans and animals bothsystemically and topically.

In vitro investigations have for instance shown that the compounds arehighly potent against a number of bacteria e.g. staphylococci,streptococci, corynebacteriae, bacteroides species, and Bacillussubtilis. In table A below the in vitro activity of some of thecompounds of the invention against a number of pathogenic organisms isshown. It can be seen that the compounds of the invention have the samestrong activity against a fusidic acid resistant strain of Staph. aureusas against a fusidic acid sensitive variant of the same strain. Thisclearly shows that there is no cross resistance between fusidic acid andthe compounds of the invention. Although less active against fusidicacid sensitive staphylococci than fusidic acid, the compounds of theinvention show a similar or even better activity against streptococci,Bacteroides fragilis and Corynebacterium acnes when compared withfusidic acid.

                                      Table A                                     __________________________________________________________________________    Concentration required for 50% inhibition (IC.sub.50) in μg/ml                           Ex.                                                                              Ex. Ex. Ex.                                                                              Ex.                                                                              Ex.                                                                              Ex.                                                                              Ex.                                                                              Ex.                                                                              Ex.                                                                              Ex.                                                                              Fusidic                      Organisms     1  2   8   11 13 14 23 26 27 31C                                                                              31D                                                                              acid                         __________________________________________________________________________    Streptococcus pyogenes                                                        Leo EC        0.5                                                                              0.2 0.5 1.6                                                                              0.63                                                                             0.32                                                                             0.63                                                                             0.5                                                                              0.63                                                                             0.5                                                                              0.63                                                                             0.63                         Streptococcus sp.                                                             Leo EG2       1.6                                                                              0.5 0.5 1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              0.5                                                                              1.0                                                                              0.63                                                                             0.79                                                                             1.6                          Staphylococcus aureus                                                         Leo CC178B    1.6                                                                              6.3 2   2.7                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              0.025                        Staph. aureus, Leo                                                            CC178H.sub.2 (fusidic acid                                                    resistant strain)                                                                           1.6                                                                              10  2.5 3.2                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              1.6                                                                              32                           Staph. aureus Leo                                                             CJ145         3.2                                                                              100     3.2                                                                              7.9                                                                              5.0                                                                              7.9   4.0                                                                              4.0                                                                              5.0                                                                              16                           Bacteroides fragilis,                                                         Leo JA2       20 13  >100                                                                              2  2  4  16 20 10 6.3   1.6                          Corynebact. acnes                                                             Leo FN        0.5                                                                              0.63                                                                              1.6 2  0.5                                                                              1.6                                                                              0.79                                                                             0.5                                                                              0.63                                                                             0.63                                                                             1.6                                                                              0.2                          __________________________________________________________________________

In vitro investigations have further shown that the antibacterial effectof the compounds is highly bactericidal even under conditions where theeffect of fusidic acid is solely bacteriostatic. Furthermore, it hasbeen found that combinations consisting of one or more of the compoundsof the invention and fusidic acid or other fusidic acid derivatives,such as dihydrofusidic acid and compounds of our copending U.S. patentapplication Ser. No. 693,976 show an effect exceeding the additiveeffect of the single components. Also, by use of such a combination thedevelopment of resistance against each of the components can beprevented.

Furthermore, the compounds of the invention are chemically more stablethan fusidic acid, a fact which is of practical importance, e.g. in thepreparation of formulations for topical use. Like fusidic acid they areabsorbed efficiently from the gastro-intestinal tract and arepractically non-toxic.

The compounds of formula I can be prepared by a method comprising afirst step in which an intermediate of the general formula II is formed.##STR3##

In formula II Q₁ ' stands for Q₁ as defined above or for ##STR4## R₃representing an alkanoyl, an aralkanoyl or an aroyl radical; R₁, A, Q₂and the dotted line between C-24 and C-25 have the meaning as definedabove; R₂ represents a benzyl radical or a substituted benzyl radical,such as a p-nitrobenzyl or p-methoxybenzyl radical.

The compounds of formula II can be prepared according to one of thefollowing methods:

A. A compound of the general formula III is reacted with a compound ofthe general formula IV to give a compound of the general formula II:##STR5## In these formulae Q₁ ', Q₂, R₁, A, R₂ and the dotted linebetween C-24 and C-25 have the meaning as defined above, X stands forhydrogen or a cation, such as Na⁺, K⁺, Ag⁺, an ammonium, ortrialkylammonium ion, and Y is a chlorine, bromine or an iodine atom.The reaction is performed in an inert organic solvent, e.g.dimethylformamide, and at room temperature or at slightly elevatedtemperature.

B. A compound of the general formula V is reacted with a compound of thegeneral formula VI to form a compound of formula II. ##STR6## In theseformulae Q₁ ', Q₂, R₂, Y, R₁, A and the dotted line between C-24 andC-25 have the meaning as defined above. If A in formulae II and VIrepresents oxygen, the reacting compounds of formula VI may preferablybe used as solvents, and the reaction is performed in the presence of asilver or mercury salt, e.g. silver carbonate, silver trifluoroacetateor mercuric acetate, or a base, e.g. potassium carbonate, sodiumcarbonate or sodium alcoholate, and at room temperature or at slightlyelevated temperature. If A in formulae II and VI stands for sulphur, thereaction is performed in an inert organic solvent, preferably ethanoldimethylsulfoxide or dimethylformamide, in the presence of a base, e.g.sodium or potassium hydroxide or sodium hydride, and at or below roomtemperature or at slightly elevated temperature.

C. Compounds of the general formula II, in which A stands for sulphurand R₁ is aryl or aromatic heterocyclyl, can be prepared by reacting acompound of the general formula V, in which Y stands for a hydroxylgroup, with a phosphine, e.g. tributylphosphine or triphenylphosphine,and a compound of the general formula R₁ SR₁. The reaction is performedeither without a solvent or in an inert organic solvent, preferablydimethylformamide or pyridine, at or below room temperature.

The preparation of the starting compounds of formulae III and V isdescribed in our co-pending U.S. patent application Ser. No. 693,976 inwhich application also methods are given for the preparation of theintermediate compounds of formula II.

In a final step the compounds of formula II are converted into thecompounds of formula I or salts thereof by reaction with a base, such asaqueous sodium or potassium hydroxide, sodium hydride or potassium tert.butylate, in the presence of an organic solvent.

If this solvent is dimethylsulfoxide, the reaction proceeds especiallyrapidly and gives outstanding yields of the pure compounds. This isprobably due to the formation of the carbanion ##STR7## when thissolvent is brought into contact with a base. This ion, acting as anextraordinary soft base, catalyses the isomerisation of the double bond,thus giving rise to the formation of compounds of formula I (with adouble bond between C-13 and C-17) instead of compounds of formula III(with a double bond between C-17 and C-20), which are the major productswhen other solvents are used, as described in our co-pending U.S. patentapplication Ser. No. 693,976.

Compounds of the invention containing a single bond between C-24 andC-25 can also be prepared from the corresponding unsaturated analoguesby reduction, e.g. a catalytic hydrogenation using, for instance,palladium on carbon as a catalyst.

The compounds of the invention, in which Q₁ and/or Q₂ stand for anoxygen atom, can also be prepared from the corresponding compounds, inwhich Q₁ and Q₂ stand for ##STR8## by a suitable oxydation process.

The easily hydrolysable esters of the compounds of formula I can beprepared in known manner by methods described in the literature.

The compounds of the invention prepared according to these methodsconsist of mixtures of the two possible C-20-isomers. These mixtures canbe separated into the two pure isomers by conventional methods, e.g.fractionate crystallization or chromatographic procedures.

It is a further object of the present invention to providepharmaceutical compositions which are useful in the treatment ofinfectious diseases in the human and veterinary practice.

With this object in view, the compositions of the invention contain asan active component at least one member selected from the groupconsisting of compounds of formula I, salts thereof with non-toxic,pharmaceutically acceptable bases, and easily hydrolysable estersthereof, together with solid or liquid pharmaceutical carriers and/ordiluents.

In the said compositions, the proportion of therapeutically activematerial to carrier substance can vary between 1% and 95% by weight. Thecompositions can be worked up to various pharmaceutical forms ofpresentation, such as granulate, tablets, pills, dragees, suppositories,capsules, sustained-release tablets, suspensions, injection medicine, orso far as mixtures are concerned, they may be filled in bottles or tubesor similar containers. Pharmaceutical organic or inorganic, solid orliquid carriers and/or diluents suitable for oral, enteral, parenteralor topical administration can be used to make up compositions containingthe present compounds. Water, gelatine, lactose, starch, magnesiumstearate, talc, vegetable and animal oils and fats, benzyl alcohol, gum,polyalkylene glycol, petroleum jelly, cocoa butter, lanolin or otherknown carriers for medicaments are all suitable, while stabilizingagents, wetting and emulsifying agents, salts for varying the osmoticpressure or buffers for securing an adequate pH-value of the compositioncan be used as auxiliary agents.

Furthermore, the composition may contain other pharmaceutically activecomponents which can appropriately be administered together with thecompounds of the invention in the treatment of infectious diseases, suchas other suitable antibiotics, in particular such antibiotics, which mayenhance the activity and/or prevent development of resistance. Suchantibiotics include fusidic acid and other fusidic acid derivatives,β-lactam antibiotics, tetracyclines, rifamycins, erythromycin,lincomycin, and clindamycin. Other compounds which advantageously may becombined with the compounds of the invention, especially in topicalpreparations, include e.g. corticosteroids, like hydrocortisone,triamcinolone or fluocinolone.

For granulates, tablets, capsules or dragees the pharmaceuticalcomposition of the invention appropriately contains from 25 percent to95 percent of the active substance of the invention, and in oralsuspensions the corresponding amount is appropriately from 2-25 percent.

For parenteral use the compounds of the invention are preferably givenby injection of pharmaceutical compositions containing from 1 to 20percent of the active ingredient.

When the compounds of formula I are administered in the form of saltswith pharmaceutically acceptable, non-toxic bases, the preferred saltsare for instance the sodium salts or the diethanolamine salts, but otherpharmaceutically acceptable and non-toxic salts may be used.

As indicated above, the compounds of formula I, their salts and easilyhydrolysable esters may be worked up to pharmaceutical forms ofpresentation including suspensions, powders, ointments and creams. Apharmaceutical preparation for oral treatment may also be in the form ofa suspension containing either a compound of formula I or a sparinglysoluble salt thereof with a pharmaceutically acceptable base or aneasily hydrolysable ester thereof in an amount of from 20 to 100 mg perml of vehicle. A pharmaceutical preparation for topical treatment may bein the form of a powder, an ointment or a cream containing a compound ofthe invention in an amount of from 0.5 to 10 g per 100 g of preparation.

Another object of the invention resides in the selection of a dose ofthe compounds of the invention which dose can be administered so thatthe desired activity is achieved without simultaneous secondary effects.In the human therapy, the compounds of the invention are convenientlyadministered (to adults) in dosage units containing not less than 50 mgand up to 1000 mg, preferably from 250 to 750 mg, calculated as acompound of formula I.

By the term "dosage unit" is meant a unitary, i.e. a single dose whichis capable of being administered to a patient, and which may be readilyhandled and packed, remaining as a physically stable unit dosecomprising either the active material as such or a mixture of it withsolid or liquid pharmaceutical diluents or carriers.

In the form of a dosage unit, the compound may be administered once ormore times a day at appropriate intervals, always depending, however, onthe condition of the patient, and in accordance with the prescriptionmade by the medical practitioner.

Thus in systemic treatment a daily dose will be from 0.25 g to 4 g perday, preferably an amount of from 0.5 to 3 g, calculated as a compoundof formula I.

By the term "dosage unit" is in connection with the topical use meant aunitary, i.e. a single dose capable of being administered topically tothe patients and applicating per sq. centimeter of the infected areafrom 0.1 mg to 10 mg and preferably from 0.2 mg to 1 mg of the compoundin question.

If the composition is to be injected, a sealed ampoule, a vial or asimilar container may be provided containing a parenterally acceptableaqueous or oily injectable solution or dispersion of the active materialas the dosage unit.

The parenteral preparations are in particular useful in the treatment ofconditions in which a quick response to the treatment is desirable. Inthe continuous therapy of patients suffering from infectious diseases,the tablets or capsules may be the appropriate form of pharmaceuticalpreparation owing to the prolonged effect obtained when the drug isgiven orally, in particular in the form of sustained-release tablets.

In the treatment of infectious diseases, such tablets may advantageouslycontain other active components, as mentioned hereinbefore.

Still another object of the invention is to provide a method of treatingpatients suffering from infectious diseases, the method comprisingadministering to patients from 0.25 g to 4 g per day, preferably from0.5 to 3 g per day, calculated as a compound of the formula I, or anequivalent amount of a salt or an ester as defined before of a compoundof the formula I. Preferably, the compound is given in the form of thedosage units aforesaid.

The invention will be further described in the following Examples whichare not to be construed as limiting the invention.

EXAMPLE 1 3α,11α-Dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oicacid sodium salt

To an icecooled solution of 3-acetyl-16-epideacetylfusidic acid benzylester (15 g; 25 mmol) and diphenyldisulfide (13.5 g, 62 mmol) in drypyridine (100 ml) was added tributylphosphine (30 ml; 126 mmol), and themixture was left at 5° C. After 3 days, additional amounts ofdiphenyldisulfide (3.4 g, 16 mmol) and tributylphosphine (7.5 ml; 31.5mmol) were added, and after a total period of 5 days at 5° C. a mixtureof dimethylsulfoxide (100 ml) and 30 percent aqueous sodium hydroxide(50 ml) was added, and the resulting suspension was heated to 70° C. for3 hours. After cooling to 20° C., ether (1 liter), water (3 liter), andsaturated aqueous sodium chloride (100 ml) was then added with stirringcausing the desired product to precipitate as colourless crystals. After1 hour of stirring, the organic phase containing the crystals wasfiltered, and the crystals were washed with water (100 ml) and ether(200 ml), and dried to yield3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acid sodiumsalt as a mixture of the two C-20-isomers; melting point 243°-247° C.

    ______________________________________                                        Found:      C 63.65, H 8.62, S 4.84,                                                                             H.sub.2 O 10.4%                            C.sub.35 H.sub.49 NaO.sub.4 S,4H.sub.2 O                                      Requires:   C 63.59, H 8.69, S 4.85,                                                                             H.sub.2 O 10.9%                            ______________________________________                                    

EXAMPLE 2 The sodium salt of3α,11α-dihydroxy-16β-(4'-bromophenylthio)fusida-13(17), 24-dien-21-oicacid

Following the procedure of Example 1 and substitutingdi-(4-bromophenyl)disulfide for diphenyldisulfide,3α,11α-dihydroxy-16β-(4'-bromophenylthio)fusida-13(17),24-dien-21-oicacid sodium salt was obtained as a mixture of the two C-20-isomers;melting point 231°-239° C.

    ______________________________________                                        Found:         C 61.67, H 7.63, S 4.83, Br 11.24%                             C.sub.35 H.sub.48 NaBrO.sub.4 S, H.sub.2 O                                    requires:      C 61.30, H 7.35, S 4.68, Br 11.66%                             ______________________________________                                    

EXAMPLE 3 The sodium salt of3α,11α-dihydroxy-16β-(2',5'-dichlorophenylthio)-fusida-13(17),24-dien-21-oicacid

Following the procedure of Example 1 and substitutingdi(2,5-dichlorophenyl)disulfide for diphenyldisulfide,3α,11α-dihydroxy-16β-(2',5'-dichlorophenylthio)fusida-13(17),24-dien-21-oicacid sodium salt was prepared, as a crystalline product with nowell-defined melting point. (The product is a mixture of the two C-20-isomers).

EXAMPLE 4 The sodium salt of3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acid

16-Epideacetylfusidic acid benzyl ester (3 g, 5.3 mmol) anddiphenyldisulfide (4.9 g, 23 mmol) were dissolved in pyridine (20 ml),the solution was cooled to 0° C., and tributylphosphine (5.5 ml, 23mmol) was added. After standing at 20° C. for 3 days, the solution wasdiluted with ether (100 ml), washed with 4 N hydrochloric acid (2×25ml), with 2 N sodium hydroxide (2×25 ml) and with water (2×50 ml), driedand evaporated in vacuo to yield crude16-deacetoxy-16β-phenylthiofusidic acid benzyl ester as an oil. Thisresidue was dissolved in a mixture of dimethylsulfoxide (200 ml) and 2 Naqueous sodium hydroxide (50 ml). After heating for 3 hours at 70° C.,ether (100 ml) and water (200 ml) was slowly added to the reactionmixture to precipitate the desired product as colourless crystals. Theethereal phase, containing the crystals, was filtered, and the crystalswere washed with water and ether, and dried to afford the sodium salt of3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acid in theform of a mixture of the two C-20 -isomers; melting point 243°-247° C.

EXAMPLES 5-7

Following the procedure of Example 4 and substituting the disulfideslisted in table I for diphenyldisulfide, the 16β-thioethers of3α,11α-dihydroxyfusida-13(17),24-dien-21-oic acid sodium salt in table Iwere prepared as mixtures of the two C-20-isomers.

                  Table I                                                         ______________________________________                                         ##STR9##                                                                                      Resulting compound                                           Example Disulfide      R           Mp (°C.)                            ______________________________________                                        5       Di(o-methylphenyl)                                                                           o-CH.sub.3 . C.sub.6 H.sub.4                                                              222-238                                    6       Di(m-methylphenyl)                                                                           m-CH.sub.3 C.sub.6 H.sub.4                                                                226-234                                    7       Di(p-methylphenyl)                                                                           p-CH.sub.3 C.sub.6 H.sub.4                                                                199-213                                    ______________________________________                                    

example 8 3α,11α-dihydroxy-16β-phenylthiofusida-13(17)-en-21-oic acid,sodium salt

To an icecooled mixture of 16-epideacetyl-24,25-dihydrofusidic acidbenzyl ester (6.2 g, 11 mmol) and diphenyldisulfide (6.3 g, 29 mmol) wasadded tributylphosphine (14 ml, 59 mmol), and the mixture was left at20° C. for 48 hours. 40 ml of dimethylsulfoxide and 20 ml of 30 percentaqueous sodium hydroxide were then added, and the resulting suspensionwas heated to 70° C. for two hours. After cooling to 20° C., ethyl ether(200 ml) and water (600 ml) were added. After some hours the desiredproduct precipitated as colourless crystals. After 24 hours at roomtemperature, the organic phase containing the crystals was filtered, andthe crystals were washed with water (100 ml) and ethyl ether (100 ml),and dried to yield the sodium salt of3α,11α-dihydroxy-16β-phenylthiofusida-13(17)-en-21-oic acid as a mixtureof the two C-20-isomers. This crude product was recrystallized frommethanol-water giving the analytically pure compound; melting point235°-241° C.

EXAMPLE 9 The sodium salt of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid

To a solution of potassium hydroxide (10 g; 150 mmol) and isopropylmercaptan (30 ml; 320 mmol) in pure ethanol (750 ml) was added3-acetyl-16-deacetoxy-16α-bromofusidic acid benzyl ester (24 g; 36mmol), and the resulting solution was left at room temperature for 3days. Thereafter, the major part of ethanol was removed in vacuo, and tothe residue was added ethyl acetate (200 ml) and water (100 ml). Theorganic phase was separated, washed twice with water, dried, andevaporated in vacuo to yield crude3-acetyl-16-deacetoxy-16β-isopropylthiofusidic acid benzyl ester as anoily residue.

This residue was dissolved in a mixture of 30 percent aqueous sodiumhydroxide (40 ml) and dimethylsulfoxide (200 ml). After heating for 3hours at 70° C., water (1000 ml) and ether (200 ml) was added withstirring. After 1 hour, the organic phase containing the desired productas colourless crystals was separated, the crystals were filtered of,washed with water and ether, and dried to yield3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acidsodium salt as a mixture of the two C-20-isomers.

Recrystallization from methanol-water gave the analytical sample,melting point 220°-228° C.

    ______________________________________                                        Found:         C 61.68,  H 9.32,  S 5.14%                                     C.sub.32 H.sub.51 O.sub.4 SNa, 4H.sub.2 O                                     requires:      C 61.31,  H 9.49,  S 5.12%                                     ______________________________________                                    

EXAMPLE 10-24 16β-Thioethers of3α,11α-dihydroxy-fusida-13(17),24-dien-21-oic acid sodium salt

Following the procedure of Example 5 and substituting the mercaptanslisted in table II for isopropyl mercaptan, the 16β-thioethers of3α-11α-dihydroxy-fusida-13(17),24-dien-21-oic acid sodium salt listed intable I were prepared as mixtures of the two C-20-isomers.

                  Table II                                                        ______________________________________                                         ##STR10##                                                                                     Resulting compound                                           Example                                                                              Mercaptan       R            Mp (°C.)                           ______________________________________                                        10     methyl mercaptan                                                                              CH.sub.3     252-262                                   11     ethyl mercaptan CH.sub.2 CH.sub.3                                                                          201-210                                   12     n-butyl mercaptan                                                                             (CH.sub.2).sub.3CH.sub.3                                                                   136-145                                   13     tert-butyl mercaptan                                                                          C(CH.sub.3).sub.3                                                                          222-235                                   14     allyl mercaptan CH.sub.2 CHCH.sub.2                                                                        175-200                                   15     cyclohexyl mercaptan                                                                          cyclohexyl   >250                                      16     n-heptyl mercaptan                                                                            (CH.sub.2).sub.6CH.sub.3                                                                   196-210                                   17     n-dodecyl mercaptan                                                                           (CH.sub.2).sub.11CH.sub.3                                                                  116-136                                   18     thiophenol      C.sub.6 H.sub.5                                                                            243-247                                   19     benzyl mercaptan                                                                              CH.sub.2 C.sub.6 H.sub.5                                                                   210-222                                   20     2-phenylethyl-  CH.sub.2 CH.sub.2 C.sub.6 H.sub.5                                                          234-242                                          mercaptan                                                              21     4-tert-butyl-thio-                                                                            4-C.sub.6 H.sub.4 C(CH.sub.3).sub.3                                                        215-225                                          phenol                                                                 22     thio-2-naphthol 2-naphthyl   145-165                                   23     furfuryl mercaptan                                                                            2-furfuryl   216-221                                   24     2-pyridyl mercaptan                                                                           2-pyridyl    216-221                                   ______________________________________                                    

EXAMPLE 253α,11α-Dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acidsodium salt

To a solution of 3-O-acetyl-16-deacetoxy-16α-bromofusidic acid benzylester (33.5 g, 50 mmol) in 75 ml of dimethylsulfoxide was added asolution of sodium hydroxide (2.4 g, 60 mmol) and isopropyl mercaptan in25 ml of ethanol. After stirring at room temperature for 2 hours, 30percent aqueous sodium hydroxide (25 ml) was added, and the resultingmixture was heated to 70° C. for 2 hours. After cooling to 20° C., water(500 ml), 4-methyl-2-pentanone (500 ml), and 4N aqueous hydrogenchloride (400 ml) were added. The organic phase was collected, washedwith water, and filtered. The resulting solution was stirred, while 2Naqueous sodium hydroxide (100 ml) was slowly added causing the desiredproduct to precipitate as colourless crystals. After cooling to 5° C.for 2 hours, the crystals were filtered off, washed with water (2× 10ml) and 4 -methyl-2-pentanone (2× 10 ml), and dried to yieldanalytically pure 3α ,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid sodium salt as a mixture of the two C-20-isomers;melting point 243°-248° C.

EXAMPLE 26 3α,11α-Dihydroxy-16β-isopropylthiofusida-13(17)-en-21-oicacid sodium salt

Following the procedure of Example 25 and substituting3-O-acetyl-16-deacetoxy-24,25-dihydro-16α-bromofusidic acid benzyl esterfor the corresponding 24,25-unsaturated compound,3α,11α-dihydroxy-16β-isopropylthiofusida-13(17)-en-21-oic acid wasprepared as a crystalline sodium salt; melting point 215°-240° C.(dec.).

EXAMPLE 273α,11α-Dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid

The sodium salt of3α,11α-dihydroxy-16β-isopropyl-thiofusida-13(17),24-dien-21-oic acid (10g), prepared as described in Example 25, was dissolved in methanol (150ml), and 1N aqueous hydrochloric acid (17.5 ml) was added. The resultingsolution was stirred at 20° C., while 22.5 ml of water was slowly addedcausing the desired product to crystallize. After stirring for 2 hours,the crystals were filtered off, washed with methanol-water (4/1), anddried to yield 7.0 g of a mixture of the two C-20-isomers of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid,melting point 130°-134° C.; [α]_(D) ²⁰ =-92.9° (C=1, chloroform). To themother liquor 10 ml of water was added, causing an additional amount ofonly one of the two isomers to precipitate as colourless crystals, whichwere collected and recrystallized from methanol-water to give one of thetwo C-20-isomeric acids (360 mg) in a pure state, melting point109°-113° C. [α]_(D) ²⁰ =-37.8° (C=1, chloroform).

(This product is identical with that of Example 31C).

EXAMPLE 283α,11α-dihydroxy-16β-(2'-aminoethylthio)fusida-13(17),24-dien-21-oicacid A. 3-Acetyl-16-deacetoxy-16β-(2'-aminoethylthio)fusidic acid benzylester

3-Acetyl-16-deacetoxy-16α-bromofusidic acid benzyl ester (2.68 g; 4mmol) was added to a solution of potassium hydroxide (8.64 g; 130 mmol)and the hydrochloride of cystein amine (9.0 g; 80 mmol) in 150 ml ofpure ethanol. After stirring for 16 hours at room temperature, water(200 ml) was slowly added to crystallize the desired compound.

The crystals were filtered off, washed with a mixture of water (10 ml)and ethanol (10 ml), and dried to yield3-acetyl-16-deacetoxy-16β-(2'-aminoethylthio)fusidic acid benzyl ester(2.49 g); melting point 150°-173° C.

Recrystallization from methanol-water gave the analytical sample,melting point 184°-186° C.

    ______________________________________                                        Found:   C 71.61,  H 8.92,  S 4.81,                                                                              N 2.04%                                    C.sub.40 H.sub.59 O.sub.5 NS                                                  requires:                                                                              C 72.15,  H 8.93,  S 4.81,                                                                              N 2.10%                                    ______________________________________                                    

B. 3α,11α-dihydroxy-16β-(2'-aminoethylthio)fusida-13(17),24-dien-21-oicacid

600 mg of the above benzyl ester was dissolved in a mixture ofdimethylsulfoxide (50 ml) and 2 N aqueous sodium hydroxide (10 ml).After heating to 70° C. for 1.5 hour, water (250 ml) was added.Adjustment of the pH-value to 6.0 by addition of 4 N aqueoushydrochloric acid caused an amorphous product to precipitate. This crudeproduct was filtered off, dried and dissolved in boiling ethyl acetate(150 ml). When this solution was allowed to cool to room temperaturewith stirring, an amorphous precipitate was formed. The3α,11α-dihydroxy-16β-(2'-aminoethylthio)fusida-13(17),24-dien-21-oicacie thus obtained was filtered off, and dried to yield a mixture of thetwo C-20 isomers.

    ______________________________________                                        Found:   C 65.80,  H 9.54,  S 5.59,                                                                              N 2.40%                                    C.sub.31 H.sub.51 No.sub.4 S                                                  requires:                                                                              C 65.34,  H 9.73,  S 5.63,                                                                              N 2.46%                                    ______________________________________                                    

The NMR spectrum (CD₃ OD) shows a signals at δ= 0.09 (d, 3H), 1.01(s,3H), 1.21 (bs, 6H), 1.59 and 1.65 (2 bs, 6H), 2.5-2.4 (m, 4H; --SCH₂CH₃.4 .sup.⊕ NH₃), 3.61 (m, 1H; CH-3), 3.78 (m, 1H; CH-20), 4.31 (m, 1H,CH-11) and 5.13 (m, 1H; CH-24) ppm. Tetramethylsilane was used asinternal reference.

EXAMPLE 20 3α,11α-dihydroxy-16β-(2'-hydroxyethylthio)fusida-13(17),24-dien-21-oic acid A. 3-Acetyl-16-deacetoxy-16β-(2'-hydroxyethylthio)fusidic acid benzyl ester

3-Acetyl-16-deacetoxy-16α-bromofusidic acid benzyl ester (1.34 g, 2mmol) was added to a solution of potassium hydroxide (1.68 g, 25 mmol)and 2-hydroxyethyl mercaptan (2.1 ml, 30 mmol) in 150 ml of pureethanol. After stirring for 16 hours at room temperature, water (100 ml)was added slowly to crystallize the desired compound. The crystals werefiltered off, washed with a mixture of water (5 ml) and methanol (5 ml),and dried to yield3-acetyl-16-deacetoxy-16β-(2'-hydroxyethylthio)fusidic acid benzyl ester(1.18 g); melting point 167°-176° C.

Recrystallization from methanol-water raised the melting point to175°-178° C.

B.3α,11α-dihydroxy-16β-(2'-hydroxyethylthio)fusida-13(17),24-dien-21-oicacid 700 mg of the above benzyl ester was dissolved in a mixture ofdimethylsulfoxide (50 ml) and 2 N aqueous sodium hydroxide (10 ml).After heating to 70° C. for 1.5 hour, the mixture was acidified with 4 Nhydrochloric acid (pH=2) and water (100 ml) and ether (100 ml) wasadded. The organic phase was separated, washed with water (5×50 ml),dried, and evaporated in vacuo to give an oily residue, containing thetwo isomers of the desired product. This residue was separated into twofractions by dry column chromatography on silica gel(cyclohexan:chloroform:acetic acid, 10:80:10).

The more polar of these two fractions separated by dry columnchromatography contained one of the two C-20-isomers of3α,11α-dihydroxy-16β-(2'-hydroxyethylthio)fusida-13(17),24-dien-21-oicacid (290 mg) and the less polar contained 50 mg of the other isomer.The NMR spectrum (CDCl₃) of the more polar C-20-isomer shows signals at1.00(s, 3H), 1.21 (bs, 3H), 1.25 (s, 3H), 1.61 and 1.69 (2 bs, 6H), 2.75(m, 2H, CH₂ S), 3.5-3.9 (m, 5H, CH-3, CH-16, CH-20 and CH₂ OH), 4.40 (m,1H, CH-11) and 5.06 (m, 1H, CH-24) ppm. Tetramethylsilane was used asinternal reference. The NMR spectrum (CD₃ OD) of the less polarC-20-isomer shows signals at 0.86 (d, J=7, 3H), 0.97 (s, 3H), 1.13 (s,3H), 1.20 (s, 3H), 1.56 and 1.61 (2bs, 6H), 2.62 (m, 2H, SCH₂), 3.5-3.8(m, 5H, CH-3, CH-16, CH-20 and CH₂ OH), 4.27 (m, CH-11) and 5.15 (m, 1H,CH-24) ppm. Tetramethylsilane was used as internal reference.

EXAMPLE 30 Separating the two C-20 -isomers of3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acid

A suspension of the sodium salt of3α,11α-dihydroxy-16β-phenylthiofusida- 13(17), 24-dien-21-oic acid (1 gof the mixture of isomers prepared according to Example 1) in a mixtureof ether (50 ml) and 1 N aqueous hydrochloric acid (10 ml) was shakenuntil the crystals had disappeared. The organic phase was separated,washed twice with water, dried, and evaporated in vacuo. The residue wasdissolved in 5 ml of boiling cyclohexane. Upon cooling to roomtemperature, a crystalline product separated, which was filtered off,washed with 1 ml of cyclohexane and dried. Recrystallization from 5 mlof cyclohexane yielded one of the two C-20-isomers in a pure state withmelting point 96°-98° C.

The mother liquor was evaporated in vacuo and the residue wascrystallized from ether-petroleum ether to yield 210 mg of the otherC-20-isomer, purified by recrystallization from ether-petroleum ether toshow a melting point of 94°-99° C. According to thin layerchromatography (Solvent system: chloroform: cyclohexane:methanol:aceticacid, 80:10:2.5:10; spray reagent: Sulphuric acid) the latter product isthe less polar of the two isomers.

EXAMPLE 31 Separating the two C-20-isomers of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid A.One C-20-isomer of3α-O-formyl-11α-hydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oicacid acetoxymethylester

The sodium salt of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid, asprepared in Example 25 (1.5 g, 2.5 mmol) was dissolved indimethylformamide (15 ml) and chloromethyl acetate (0.3 ml, 3.3 mmol)was added. After standing for 16 hours at 20° C., the reaction mixturewas cooled to 0° C. and stirred while thionylchloride (1 ml, 13.7 mmol)was slowly added. After stirring for one hour at 20° C. ethyl ether (100ml) was added and the resulting mixture was washed with water (4×50 ml),dried and evaporated to yield 1.4 g of a mixture of the twoC-20-isomeric esters. This residue was dissolved in petroleum ether (15ml) and upon scratching one of the two isomers crystallized in a purestate. The crystals were collected, washed with petroleum ether anddried to yield the desired compound, melting point 126°-128° C.

B. The other isomer of3α-O-formyl-11α-hydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oicacid acetoxymethyl ester

The mother liquor from the crystallization of the compound of part A ofthis Example was evaporated in vacuo, and the residue was purified bychromatography on silica gel (cyclohexane:ethyl acetate, 8:2) to givethe desired compound as an oily residue.

C. One C-20-isomer of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid

The compound of part A of this Example (300 mg) was dissolved inmethanol (15), potassium carbonate (300 mg) was added, and the mixturewas stirred at room temperature for one hour. The reaction mixture wasthen evaporated in vacuo and ethyl ether (50 ml) and 1 N hydrochloricacid (25 ml) was added. The organic phase was separated, washed twicewith water and evaporated to yield a crude product, which wascrystallized from methanol/water to yield one isomer of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid,melting point 110°-112° C.; [α]_(D) ²⁰ =-37.8° (C=1 in chloroform).

D. The other C-20-isomer of3α,11α-dihydroxy-16β-isopropylythiofusida-13(17),24-dien-21-oic acid

By following the procedure of part C of this Example but substitutingthe product of part B for that of part A the other isomer of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17), 24-dien-21-oic acid wasprepared as colourless crystals, melting point 144°-149° C.; [α]_(D) ²⁰=-158.7° (C=1 in chloroform).

EXAMPLE 323α-Hydroxy-11-keto-16β-isopropylthiofusida-13(17),24-dien-21-oic acid

A solution of3α-O-formyl-11α-hydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oicacid acetoxymethyl ester (300 mg of the isomer described in Example 31A. in 5 ml of methylene chloride was added to a stirred suspension ofpyridinium chlorochromate (600 mg) in 5 ml of methylene chloride. Afterstirring at room temperature for one hour, ethyl ether (100 ml) wasadded and the stirring was continued for 30 minutes. Filtration andevaporation afforded3α-O-formyl-11-keto-16β-isopropylthiofusida-13(17),24-dien-21-oic acidacetoxymethyl ester as an oily residue, which was dissolved in methanol(15 ml). Potassium carbonate (300 mg) was added and the resultingsuspension was stirred for one hour at room temperature, and thenevaporated in vacuo. Ethyl ether (50 ml) and 1N hydrochloric acid (20ml) were added to the residue, the organic phase was separated, washedtwice with water, dried and evaporated to yield a crude product, whichwas purified by chromatography on silica gel (Ethyl ether: petroleumether: acetic acid; 70:30:1/2) to yield3α-hydroxy-11-keto-16β-isopropylthiofusida-13(17),24 -dien-21-oic acidas a colourless foam.

EXAMPLE 333-Keto-11α-hydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid

The sodium salt of 3-keto-16-deacetoxy-16β-isopropylthiofusidic acid(553 mg, 1 mmol) was dissolved in 5 ml of dimethylformamide, and benzylbromide (0.15 ml, 1.2 mmol) was added. After standing at 20° C. for 18hours, the reaction mixture was diluted with ethyl ether (25 ml), washedwith water (4×25 ml), dried, and evaporated. The residue, containing thebenzyl ester of the starting compound, was dissolved in a mixture ofdimethylsulfoxide (20 ml) and 2N aqueous sodium hydroxide (10 ml). Afterheating for 3 hours at 70° C., ethyl ether (100 ml) and 4N hydrochloricacid (10 ml) were added to the reaction mixture. The organic phase wasseparated, washed twice with water, dried and evaporated to yield acrude product, which was purified by chromatography on silica gel(cyclohexane:ethyl acetate, 1:1) to yield3-keto-11α-hydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid asa foam.

EXAMPLE 34 3α,11α-Dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oicacid acetoxymethyl ester

The sodium salt of3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acid (330mg, 0.5 mmol; the more polar of the two isomers, as separated in Example26) was dissolved in 2 ml of dimethylformamide, and chloromethyl acetate(50 μl, 0.55 mmol) was added. After standing at room temperature for 16hours, ether (50 ml) was added, and the resulting mixture was washedwith water (4×50 ml), dried, and evaporated to yield3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-24-oic acidacetoxymethyl ester (one of the two possible C-20-isomers) as acolourless foam (180 mg). The NMR spectrum (CDCl₃) shows signals atδ=0.88 (d, J=6, 3H), 0.97 (s, 3H), 1.16 (bs, 6H), 1.59 and 1.67 (2 bs,6H), ##STR11## 3.52 (m, CH-20), 3.63 (m, CH-3), 4.16 (bd, CH-16), 4.29(m, CH-11), 5.12 (m, CH-24), 5.67 and ##STR12## and 7.1-7.5 (5 H,aromatic CH) ppm. Tetramethylsilane was used as internal reference.

EXAMPLE 35 3α,11α-Dihydroxy-163-phenylthiofusida-13(17),24-dien-21-oicacid fusidyloxymethyl ester

Following the procedure of Example 34 and substituting fusidic acidchloromethyl ester for chloromethyl acetate,3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acidfusidyloxymethyl ester was prepared as a colourless foam.

EXAMPLE 36 3α,11α-Dihydroxy-163-methoxyfusida-13(17),24-dien-21-oic acidsodium salt A. 16-Deacetoxy-163-methoxyfusidic acid benzyl ester

A solution of 16-deacetoxy-16β-methoxyfusidic acid (1.71 g; 3.5 mmol) inmethanol (50 ml) was titrated with 2 N methanolic sodium hydroxide usingphenolphthalcin as an indicator. After evaporation to dryness in vacuo,the amorphous sodium salt thus obtained was dissolved indimethylformamide (10 ml), benzyl bromide (0.54 ml; 4.5 mmol) was added,and the mixture was stirred at room temperature for 18 hours. Upondropwise additions of methanol:water 1:1 (30 ml) to the stirred reactionmixture, precipitation of a colourless crystalline product occurred. Thecrystals were filtered off, washed with methanol: water 1:1, and driedto afford the desired compound, melting point 179°-182° C.

B. 3α,11α-Dihydroxy-16β-methoxyfusida 13(17),24-dien-21-oic acid sodiumsalt

To a solution of 16-deacetoxy-16β-methoxyfusidic acid benzyl ester (500mg; 0.86 mmol) in dimethyl sulphoxide (25 ml) was added 2 N aqueoussodium hydroxide (5 ml), and the mixture was stirred at 70° C. for 1.5hours. After cooling to room temperature, water (25 ml) was addeddropwise to the stirred reaction mixture whereby a crystalline productprecipitated. The crystals were collected, washed with methanol:water1:1, and dried to yield the sodium salt of3α,11α-dihydroxy-16β-methoxyfusida-13(17),24-dien-21-oic acid (mixtureof C-20 isomers), melting point 224°-228° C. (dec.)

    ______________________________________                                        Found:           C 66.82,   H 9.33%                                           C.sub.30 H.sub.47 O.sub.5 Na, 1.5 H.sub.2 O                                   requires:        C 67.01,   H 9.37%                                           ______________________________________                                    

EXAMPLES 37-39 Additional3α,11α-dihydroxy-16β-alkyloxyfusida-13(17),24-dien-21-oic acid sodiumsalts

By substituting 16-deacetoxy-16β-ethoxyfusidic acid,16-deacetoxy-16β-(2'-fluoroethoxy)fusidic acid and16-deacetoxy-16β-(2',2',2'-trifluoroethoxy)fusidic acid for the16-deacetoxy-16β-methoxyfusidic acid in the procedure of Example 33, thesodium salts of the3α,11α-dihydroxy-16β-alkyloxyfusida-13(17),24-dien-21-oic acids(mixtures of C-20 isomers) listed in table III were prepared.

                  Table III                                                       ______________________________________                                         ##STR13##                                                                    Example      R            Mp (°C.)                                     ______________________________________                                        37          CH.sub.2 CH.sub.3                                                                           216-220 (dec)                                       38          CH.sub.2 CH.sub.2 F                                                                         170-178 (dec)                                       39          CH.sub.2 CF.sub.3                                                                           not determined                                      ______________________________________                                    

EXAMPLE 403α,11α-Dihydroxy-16β-(2',2'2'-trifluoroethoxy)fusida-13(17),24-dien-21-oicacid

To a suspension of the sodium salt of 3α,11α-dihydroxy-16β-(2',2',2'-trifluoroethoxy)fusida-13(17),24-dien-21-oic acid (440 mg) inwater (15 ml) was added ether (15 ml), and the stirred mixture wasacidified with diluted hydrochloric acid. The organic phase wasseparated, the aqueous phase extracted with ether (10 ml), and thecombined ethereal extracts washed twice with water, dried and evaporatedin vacuo to yield the desired compound (mixture of C-20 isomers,ratio:approximately 1:1) as a colourless foam.

The above residue was crystallized from ether, the crystals werecollected and recrystallized twice from the same solvent to give one ofthe two C-20 isomeric acids in a pure state, melting point 173°-174° C.According to thin layer chromatography (solvent system:Chloroform:cyclohexane:methanol: acetic acid 80:10:2.5:10; sprayreagent: Sulphuric acid) the crystalline compound was the more polarC-20 isomer.

    ______________________________________                                        Found:        C 66.74,    H 8.56%                                             C.sub.31 H.sub.47 F.sub.3 O.sub.5                                             requires:     C 66.89,    H 8.51%                                             ______________________________________                                    

EXAMPLES 41-43 Additional pure C-20 isomers of3α,11α-dihydroxy-16β-alkyloxyfusida-13(17),24-dien-21-oic acids

Following the procedure of Example 40, but substituting the sodium saltof 3α,11α-dihydroxy-16β-methoxyfusida-13(17),24-dien-21-oic acid and thesodium salts of the corresponding 16β-ethoxy and 16β-(2'-fluoroethoxy)derivatives for the sodium3α,11α-dihydroxy-16β-(2',2',2'-trifluoroethoxy)fusida-13(17),24-diene-21-oate,one of the pure C-20 isomers of the3α,11α-dihydroxy-16β-alkyloxyfusida-13-(17),24-dien-21oic acids listedin table IV were obtained.

                  Table IV                                                        ______________________________________                                         ##STR14##                                                                     Example      R           Mp (°C.)                                     ______________________________________                                        41            CH.sub.3    163-164                                             42            CH.sub.2 CH.sub.3                                                                         175-177                                             43            CH.sub.2 CH.sub.2 F                                                                       172-173                                             ______________________________________                                    

example 44 in vitro bactericidal effect of3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acidcompared to that of fusidic acid

To two tubes containing NIH broth was added:

a. The sodium salt of3α,11α-dihydroxy-16β-phenylthiofusida-13(17),24-dien-21-oic acid (10μg/ml)

b. The sodium salt of fusidic acid (10 μg/ml)

The tubes were inoculated with Streptococcus pyogenes to give 9.2×10⁴organisms per ml, incubated at 37° C., and the viable counts weredetermined at intervals.

A third tube was treated similarly without addition of any of theantibiotics and used as a control:

    ______________________________________                                        Viable count after                                                            Tube   O hr      1.5 hr    4 hr    7 hr                                       ______________________________________                                        a      9.2 × 10.sup.4                                                                    1.4  10.sup.4                                                                           5.7 × 10.sup.2                                                                  5 × 10                               b      9.2 × 10.sup.4                                                                    1.2 × 10.sup.5                                                                    1.5 × 10.sup.5                                                                  1.3 × 10.sup.5                       control                                                                              9.2 × 10.sup.4                                                                    6.8 × 10.sup.5                                                                    2.4 × 10.sup.7                                                                  1.7 × 10.sup.8                       ______________________________________                                    

EXAMPLE 45 In vitro-effect of the combination of fusidic acid and3α,11α-dihydroxy-16β-isopropylthio-fusida-13(17),24-dien-21-oic acid

To 3 tubes containing NIH broth was added:

a. The sodium salt of fusidic acid (1 μg/ml).

b. The sodium salt of3α,11α-dihydroxy-16-isopropylthiofusida-13(17),24-dien-21-oic acid (3μg/ml).

c. A mixture of the sodium salts of fusidic acid (1 μg/ml) and3α,11α-dihydroxy-16-isopropyl-thiofusida-13(17),24-dien-21-oic acid (3μg/ml). The tubes were inoculated with Staphylococcus aureus to give1.4×10⁴ organisms per ml, incubated at 37° C. for 24 hours, and theviable counts were determined.

A fourth tube was treated similarly without addition of any of theantibiotics and used as a control:

    ______________________________________                                        Tube             Viable count                                                 ______________________________________                                        a                1.8 × 10.sup.8                                         b                1.5 × 10.sup.6                                         c                7.3 × 10.sup.0                                         control          6.2 × 10.sup.8                                         ______________________________________                                    

The surviving organisms in tube a are resistant to fusidic acid, andthose in tube b are resistant to3α,11α-dihydroxy-16β-isopropylthio-fusida-13(17),24-dien-21-oic acid,whereas the combination of the two compounds in tube c preventsdevelopment of resistance.

EXAMPLE 46 In vitro-effect of the combination of dihydro-fusidic acidand 3α,11α-dihydroxy-16β-phenylthio-fusida-13(17). 24-dien-21-oic acid

To three tubes containing NIH broth was added:

a. The sodium salt of dihydro-fusidic acid (10 μg/ml).

b. The sodium salt of3α,11α-dihydroxy-16-phenylthiofusida-13-(17),24-dien-21-oic acid (10μg/ml).

c. A mixture of the sodium salts of dihydro-fusidic acid (5 μg/ml) and3α,11α-dihydroxy-16-phenyl-thiofusida-13(17),24-dien-21-oic acid (5μg/ml).

The tubes were inoculated with Staphylococcus aureus to give 5.2 × 10⁵organisms per ml, incubated at 37° C. for 96 hours, and the viablecounts were determined.

A fourth tube was treated similarly without addition of any of theantibiotics and used as a control:

    ______________________________________                                        Viable counts after                                                           0         2        61/2     24     96 hours                                   ______________________________________                                        Con-                                                                          trol 5.2 × 10.sup.5                                                                   1.3 × 10.sup.6                                                                   4.6 × 10.sup.7                                                                 4.3 × 10.sup.8                                                                 full growth                              a             4.1 × 10.sup.5                                                                   3.1 × 10.sup.5                                                                 6.3 × 10.sup.6                                                                 full growth                              b             5.2 × 10.sup.4                                                                   1.1 × 10.sup.4                                                                 3.1 × 10.sup.6                                                                 full growth                              c             1.5 × 10.sup.5                                                                   4.1 × 10.sup.4                                                                 <10    <10                                      ______________________________________                                    

The surviving organisms in tube a are resistant to dihydro-fusidic acid,and those in tube b are resistant to3α,11α-dihydroxy-16β-phenylthio-fusida-13(17),24-dien-21-oic acid,whereas the combination of the two compounds in tube c preventsdevelopment of resistance.

EXAMPLE 47 Prevention of development of resistance against fusidic acidas a result of treating Staph. aureus with the sodium salt of3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid

After a 48 hours pretreatment of a fusidic acid sensitive strain ofStaph. aureus (Leo CC 178B) with subinhibitory concentrations of fusidicacid or the compound of Example 9. The sensitivities of the pretreatedcultures and of the original strain against the two compounds weredetermined. The determinations were made by serial dilutions inNIH-broth, inoculum size 2.10⁵ organisms/ml, and read as IC₅₀ after 18and 48 hours. The results can be seen in the following Table B:

                  Table B                                                         ______________________________________                                                  1C.sub.50 in μg/ml                                                         18 hours    48 hours                                                Isolates    Fusidic Compound  Fusidic                                                                             Compound                                  from        acid    of Ex 9   acid  of Ex 9                                   ______________________________________                                        Control culture                                                                           0.016   2         1     5                                         Fusidic acid cult.                                                                        7.9     1.6       50    5                                         Comp. of Ex 8 cult.                                                                       0.016   5         0.020 16                                        ______________________________________                                    

The emergence of resistance of the control culture against fusidic acidas seen by the incresed IC₅₀ -values after 48 hours is further increasedby the pretreatment with fusidic acid.

Only a slight decrease of the sensitivity to the compound of Example 9is seen. Pretreatment with fusidic acid did not influence the results.

Pretreatment of the culture with the compound of Example 9 totallyprohibited the emergence of resistance against fusidic acid.

EXAMPLE 48 In vitro activity of3α,11α-dihydroxy-16β-ethylthiofusida-13(17),24-dien-21-oic acid againstStaph. aureus before and after a number of transfers.

Serial dilutions of the compound above were made in liquid NIH-mediumand then heavily inoculated with either a fusidic acid sensitive strainof Staph. aureus (Leo CC 178B) or with a fusidic acid resistant variantof the same strain (Leo CC 178A).

After every 72 to 96 hours transfers were made from the tubes containingthe largest amount of the test compound showing full growth. The tablebelow shows the sensitivities read after overnight incubation.

                  Table C                                                         ______________________________________                                        IC.sub.50 in μg/ml                                                         Staph.                                                                        aureus  before  and after a certain member of transfer                        ______________________________________                                                        1st    2nd   3rd  4th  5th  6th                               Leo CC                                                                        178B    2.7     2.0    7.4   7.4  13.5 10.0 32                                (fusidic                                                                      acid sen-                                                                     sitive)                                                                       Leo CC                                                                        178A    2.7     2.3    3.8   4.3  4.2  4.0  4.0                               (fusidic                                                                      acid re-                                                                      sistant)                                                                      ______________________________________                                    

It will be seen from the table that the fusidic acid sensitive strainshows a 12 fold decrease of sensitivity to the compound in questionafter the 6th transfer, whereas the fusidic acid resistant strain hardlyshows any change in sensitivity. This is a highly unexpected phenomenon.

EXAMPLE 49

    ______________________________________                                        Cream                                                                         ______________________________________                                        3α,11α-dihydroxy-16β-isopropylthiofusida-                    13(17),24-dien-21-oic acid 20 g                                               Petrolatum                 150 g                                              Liquid paraffin            150 g                                              Spermaccti                 50 g                                               Sorbitan monopalmitate     50 g                                               Polyoxyethylene sorbitan monopalmitate                                                                   50 g                                               Water                      530 g                                                                         1000 g                                             ______________________________________                                    

Heat petrolatum, paraffin, spermaceti, sorbitanmonopalmitate, andpolyoxyethylene sorbitan monopalmitate to 70° C. and add slowly thewater at 72° C. with agitation. Continue agitation until the cream hascooled. Triturate3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid intothe cream base and homogenize using a roller mill. Fill the cream intolaquered aluminium collapsible tubes.

EXAMPLE 50

    ______________________________________                                        Ointment                                                                      ______________________________________                                        3α,11α-dihydroxy-16β-ethylthiofusida-                        13(17),24-dien-21-oic acid sodium salt                                                                   20 g                                               Liquid paraffin            138 g                                              Cetanol                    4 g                                                Lanolin anhydrous          46 g                                               Petrolatum 792 g                                                                                         1000 g                                             ______________________________________                                    

Melt paraffin, cetanol, lanolin, and petrolatum at 70° C. After coolingto below 40° C., triturate3α,11α-dihydroxy-16β-ethylthiofusida-13(17),24-dien-21-oic acid sodiumsalt. Fill the ointment into lacquered collapsible aluminium tubes.

EXAMPLE 51

    ______________________________________                                        Capsule                                                                       ______________________________________                                        3α,11α-dihydroxy-16β-isopropylthio-                          fusida-13(17)-en-21-oic acid sodium salt                                                                  250 g                                             Microcrystalline cellulose  145 g                                             Magnesium stearate          5 g                                                                           400 g                                             ______________________________________                                    

Pass the ingredients through a 60 mesh sieve and mix for 10 minutes.Fill the mixture into hard gelatin capsules No. 00 (Parke Davis & Co.)using a capsule fil weight of 400 mg.

EXAMPLE 52

    ______________________________________                                        Preparation of tablets                                                        ______________________________________                                        3α,11α-dihydroxy-16β-isopropylthiofusida-                    13(17),24-dien-21-oic acid  250 g                                             Avicel PH 101               120 g                                             STA-Rx 1500                 120 g                                             Magnesium stearate          10 g                                              ______________________________________                                    

3α,11α-dihydroxy-16β-isopropylthiofusida-13(17),24-dien-21-oic acid,Avicel and STA-Rx are mixed to together, sieved through a 0.7 mm sieveand thereafter mixed with the magnesium stearate. The mixture is pressedinto tablets each of 500 mg.

EXAMPLE 53

    ______________________________________                                        Preparation of suspension                                                     ______________________________________                                        3α,11α-dihydroxy-16β-phenylthiofusida-                       13(17),24-dien-21-oic acid                                                                             5.00 g                                               Citric acid              0.45 g                                               Sodium monohydrogenphosphate                                                                           0.70 g                                               Sucrose                  25.00 g                                              Tween 80                 0.05 g                                               Potassium sorbate        0.20 g                                               Carboxymethylcellulose-Na                                                                              0.50 g                                               Purified water           qs to 100 ml                                                                  suspension                                           ______________________________________                                    

The crystals are micronized and suspended in a solution of the citricacid, the sodium monohydrogenphosphate, the sucrose, the potassiumsorbate and the Tween 80 in 50 ml water, if necessary under slightwarming. The carboxymethylcellulose-Na is dissolved in 20 ml of boilingwater. After cooling, it is added to the other ingredients. Thesuspension is homogenized in a blender and finally purified water isadded to a total volume of 100 ml.

EXAMPLE 54

    ______________________________________                                        Cream                                                                         ______________________________________                                        3α,11α-Dihydroxy-16β-isopropylthiofusida-                    13(17),24-dien-21-oic acid (A)                                                                            10 g                                              16-Deacetoxy-16β-ethyloxyfusidic acid (B)                                                            10 g                                              Petrolatum                  150 g                                             Liquid paraffin             150 g                                             Spermaceti                  50 g                                              Sorbitan monopalmitate      50 g                                              Polyoxyethylene sorbitan monopalmitate                                                                    50 g                                              Water                       530 g                                                                         1000 g                                            ______________________________________                                    

Heat petrolatum, paraffin, spermaceti, sorbitanmonopalmitate, andpolyoxyethylene sorbitan monopalmitate to 70° C. and added slowly thewater at 72° C. with agitation. Continue agitation until the cream hascooled. Triturate A and B into the cream base and homogenize using aroller mill. Fill the cream into laquered aluminium collapsible tubes.

EXAMPLE 55

    ______________________________________                                        Ointment                                                                      ______________________________________                                        16-Deacetoxy-16β-isopropylsulphinyl                                      fusidic acid sodium salt (A.sub.2)                                                                    2.5       g                                           3α,11α-dihydroxy-16β-isopropylthio-                          fusida-13(17),24-dien-21-oic acid                                             sodium salt (B.sub.2)   7.5       g                                           Liquid paraffin         138       g                                           Cetanol                 4         g                                           Lanolin anhydrous       46        g                                           Petrolatum              802       g                                                                   1000      g                                           ______________________________________                                    

Melt paraffin, cetenaol, lanolin, and petrolatum at 70° C. After coolingto below 40° C., triturate A₂ and B₂. Fill the ointment into lacqueredcollapsible tubes.

EXAMPLE 56

    ______________________________________                                        Capsule                                                                       ______________________________________                                        Fusidic acid sodium salt    125 g                                             3α,11α-dihydroxy-16β-ethylthiofusida-                        13(17),24-dien-21-oic acid                                                    sodium salt                 125 g                                             Microcrystalline cellulose  145 g                                             Magnesium stearate          5 g                                                                           400 g                                             ______________________________________                                    

Pass the ingredients through a 60 mesh sieve and mix for 10 minutes.Fill the mixture into hard gelatin capsules No. 00 (Parke Davis & Co.)using a capsule fil weight of 400 mg.

EXAMPLE 57

    ______________________________________                                        Ointment                                                                      ______________________________________                                        Fusidic acid sodium salt (A)                                                                              10 g                                              3α,11α-dihydroxy-16β-phenylthiofusida-                       13(17),24-dien-21-oic acid                                                    sodium salt (B)             10 g                                              Liquid paraffin             138 g                                             Cetanol                     4 g                                               Lanolin anhydrous           46 g                                              Petrolatum                  792 g                                                                         1000 g                                            ______________________________________                                    

Melt paraffin, cetanol, lanolin, and petrolatum at 70° C. After coolingto below 40° C., triturate A and B. Fill the ointment into lacqueredcollapsible aluminium tubes.

EXAMPLE 58

    ______________________________________                                        Cream                                                                         ______________________________________                                        Fusidic acid (A.sub.1)      5 g                                               3α,11α-dihydroxy-16β-phenylthiofusida-                       13(17),24-dien-21-oic acid (B.sub.1)                                                                      15 g                                              Petrolatum                  150 g                                             Liquid paraffin             150 g                                             Spermaceti                  50 g                                              Sorbitan monopalmitate      50 g                                              Polyoxyethylene sorbitan mono-                                                palmitate                   50 g                                              Water                       530 g                                                                         1000 g                                            ______________________________________                                    

Heat petrolatum, paraffin,, spermacetic, seorbitanmonopalmitate, andpolyoxyethylene sorbitan monopalmitate to 70° C. and add slowly thewater at 72° C. with agitation. Continue agitation until the cream hascooled. Triturate A₁ and B₁ into the cream base and homogenize using aroller mill.

Fill the cream into lacquered aluminium collapsible tubes.

What We claim is:
 1. 3α,11α-dihydroxy-16β-(2'-methlyphenyl)thiofusida-13(17),24-dien-21-oic acid and pharmaceutically acceptable,non-toxic salts or easily hydrolysable esters thereof. 2.3α,11α-dihydroxy-16β-(3'-methylphenyl) thiofusida-13(17), 24-dien-21-oicacid and pharmaceutically acceptable, non-toxic salts or easilyhydrolysable esters thereof.
 3. 3α,11α-dihydroxy-16β-(4'-methylphenyl)thiofusida-13(17),24-dien-21-oic acid and pharmaceutically acceptable,non-toxic salts or easily hydrolysable esters thereof. 4.3α,11α-dihydroxy-16β-methylthiofusida-13(17), 24-dien-21-oic acid andpharmaceutically acceptable, non-toxic salts or easily hydrolysableesters thereof.
 5. 3α,11α-dihydroxy-16β-n-butylthiofusida-13(17),24-dien-21-oic acid and pharmaceutically acceptable, non-toxic salts oreasily hydrolysable esters thereof. 6.3α,11α-dihydroxy-16β-cyclohexylthiofusida-13(17), 24-dien-21-oic acidand pharmaceutically acceptable, non-toxic salts or easily hydrolysableesters thereof.
 7. 3α,11α-dihydroxy-16β-n-heptylthiofusida-13(17),24-dien-21-oic acid and pharmaceutically acceptable, non-toxic salts oreasily hydrolysable esters thereof. 8.3α,11α-dihydroxy-16β-benzylthiofusida-13(17), 24-dien-21-oic acid andpharmaceutically acceptable, non-toxic salts or easily hydrolysableesters thereof. 9.3α,11α-dihydroxy-16.beta.-(2-phenylethyl)thiofusida13(17),24-dien-21-oicacid and pharmaceutically acceptable, non-toxic salts or easilyhydrolysable esters thereof.